Nocturnal SpO2 Research Articles

Correlation between Heart Rate Variability and Disease Severity in Obstructive Sleep Apnea

Objective: This study aimed to investigate the variations in Heart Rate Variability (HRV) among individuals with Obstructive Sleep Apnea (OSA) and to explore the relationship between HRV, respiratory parameters, and disease severity. Methods: This prospective study included sixty participants diagnosed with OSA. Polysomnography (PSG) was utilized to assess HRV parameters, including time-domain and frequency-domain measures. Participants were categorized based on the severity of OSA, and data on hemoglobin (HGB), C-reactive protein (CRP), triglyceride (TG) levels, and nocturnal oxygen desaturation (NOD) were collected. Statistical analyses were performed to evaluate the correlations between HRV, respiratory parameters, and disease severity. Results: Among the participants, 23 (38%) had severe OSA, while 17 (28%) were habitual snorers (HS). Hemoglobin, C-reactive protein, and triglyceride levels were significantly higher in patients with severe OSA and NOD compared to HS individuals (p=0.002). Increased Epworth Sleepiness Scale (ESS) scores were associated with higher heart rates during sleep in severe OSA patients compared to HS individuals. NOD (+) patients exhibited statistically higher heart rates during sleep compared to NOD (-) patients (p=0.008). Individuals with an apnea/hypopnea index (AHI) >30, NOD (+), and the lowest SpO2 percentage overnight had significantly lower HRV compared to HS and NOD (-) individuals. Conclusions: In addition to AHI, NOD and the lowest overnight SpO2 are significant markers of elevated cardiovascular risk and are useful for assessing HRV. These findings suggest that cardiovascular risks in OSA patients are heightened both during sleep and wakefulness. Therefore, individuals with severe symptoms, especially those with excessive daytime sleepiness, high levels of NOD, and low nocturnal SpO2 percentages, should be prioritized for treatment, alongside those with high levels of severe OSA.

Sleep-disordered breathing and nocturnal hypoxemia in chronic thromboembolic pulmonary disease.

Sleep-disordered breathing (SDB) and nocturnal hypoxemia were known to be present in patients with chronic thromboembolic pulmonary hypertension (CTEPH), but the difference betweenSDB and nocturnal hypoxemia in patients who have chronic thromboembolic pulmonary disease (CTEPD) with or without pulmonary hypertension (PH) at rest remains unknown. Patients who had CTEPH (n = 80) or CTEPD without PH (n= 40) and who had undergone sleep studies from July 2020 to October 2022 at Shanghai Pulmonary Hospital were enrolled. Nocturnal mean SpO2 (Mean SpO2) <90% was defined as nocturnal hypoxemia, and the percentage of time with a saturation below 90% (T90%) exceeding 10% was used to evaluate the severity of nocturnal hypoxemia. Logistic and linear regression analyses were performed to investigate the difference and potential predictor of SDB or nocturnal hypoxemia between CTEPH and CTEPD without PH. SDB was similarly prevalent in CTEPH and CTEPD without PH (P = 0.104), both characterised by obstructive sleep apnoea (OSA). Twenty-two patients with CTEPH were diagnosed with nocturnal hypoxemia, whereas only three were diagnosed with CTEPD without PH (P = 0.021). T90% was positively associated with mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance in patients with CTEPH and CTEPD without PH (P < 0.001); T90% was also negatively related to cardiac output in these patients. Single-breath carbon monoxide diffusing capacity, sex and mPAP were all correlated with nocturnal hypoxemia in CTEPH and CTEPD without PH (all P < 0.05). Nocturnal hypoxemia was worse in CTEPD with PH; T90%, but not SDB, was independently correlated with the hemodynamics in CTEPD with or without PH.

Prediction models for respiratory event types in OSA patients based on hypoxic parameters

Objective: To analyze the hypoxic parameters in patients with obstructive sleep apnea (OSA), to explore the difference and association between different types of respiratory events and to construct predictive models for respiratory event types. Methods: Fifty patients [including 41 males and 9 females with age 18-74(45.72±13.39) years ] with OSA diagnosed by polysomnography (PSG) were selected for retrospective analysis, and all respiratory events with pulse oximetry (SpO2) desaturation in the recorded overnight data were divided into hypopnea group (Hyp, 3 316), obstructive apnea group (OA, 5 552), central apnea group (CA, 1 088) and mixed apnea group (MA, 1 369) according to the type of events, and all event records were exported separately from the PSG software as comma-separated variable (.csv) files, which were imported and analyzed using the in-house built Matlab software. A total of 13 hypoxic parameter differences were compared among the four groups, including minimum oxygen saturation of events (e-minSpO2), the depth of desaturation (ΔSpO2), the duration of desaturation and resaturation (DSpO2), the duration of desaturation (d.DSpO2), duration of resaturation (r.DSpO2), duration of SpO2<90% (T90), duration of SpO2<90% during desaturation (d.T90), duration of SpO2<90% during resaturation (r.T90), area under the curve of SpO2<90% (ST90), area under the curve of SpO2<90% during desaturation (d.ST90), area under the curve of SpO2<90% during resaturation (r.ST90), oxygen desaturation rate (ODR) and oxygen resaturation rate (ORR). Hyp model (H), OA model (O), CA model (C) and MA model (M) were constructed respectively; group differences for the different hypoxia parameters were assessed using single factor analysis and Kruskal-Wallis H test. For different categories of respiratory events, binary logistic regression was used to identify the variables included in the regression model. Receiver operating characteristic (ROC) curves were generated to assess and compare the sensitivity, specificity, positive predictive value and negative predictive value of the four models, thereby gauging the predictive precision of each model. Results: ΔSpO2, ODR, ORR, T90, d.T90, r.T90, ST90, d.ST90 and r.ST90 for each type of respiratory events showed MA>OA>CA>Hyp, and e-minSpO2 showed MA<OA<CA<Hyp. Logistic regression showed that e-minSpO2, ΔSpO2, d.DSpO2, r.DSpO2, ODR, ORR, d.T90, r.T90, d.ST90 and r.ST90 were independent predictors for Hyp, ΔSpO2, d.DSpO2, r.DSpO2, ORR, d.T90, r.T90, d.ST90 and r.ST90 were independent predictors for OA, ΔSpO2, d.DSpO2, r. DSpO2, ODR, ORR, r.T90, d.ST90 and r.ST90 were independent predictors for CA, while e-minSpO2, ΔSpO2, d.DSpO2, r.T90, d.ST90 and r.ST90 were independent predictors for MA. The area under the ROC curve (AUC) of the H, O, C, and M models were 0.875, 0.751, 0.755, and 0.749, respectively, and all models had high specificity (0.865, 0.722, 1.000, and 0.993, respectively) and negative predictive values (0.871, 0.692, 0.904, and 0.881, respectively). Conclusions: Four predictive models for respiratory event types can be constructed based on hypoxic parameters, providing a feasible novel tool for applying nocturnal SpO2 to automatically identify respiratory event types.

Hyperoxic ventilatory response in infants is related to nocturnal hypoxaemia

BackgroundThe carotid bodies primarily serve as oxaemia sensors that affect tidal breathing. Their function has not yet been studied in infants with nocturnal hypoxaemia. This cross-sectional study aimed to characterise the hyperoxic ventilatory response (HVR) in infants and its relationship to nocturnal hypoxaemia.MethodsThe HVR was analysed in term infants aged &lt;24 months with childhood interstitial lung disease (chILD), those with severe recurrent wheezing (wheeze), and nonrespiratory controls. The HVR timing was characterised using hyperoxia response time (HRT1), and HVR magnitude was characterised by the relative change in minute volume between normoxia and 30-s hyperoxia (VE_dH30). Time spent with an arterial haemoglobin oxygen saturation (SpO2) &lt;90% during overnight monitoring (t90) was estimated.ResultsHVR data were available for 23 infants with chILD, 24 wheeze and 14 control infants. A significant decrease in minute volume under 30 s of hyperoxia was observed in all patients. HRT1 was shorter in chILD (5.6±1.2 s) and wheeze (5.9±1.5 s) groups than in the controls (12.6±5.5 s) (ANOVA p&lt;0.001).VE_dH30 was increased in the chILD group (24.3±8.0%) compared with that in the controls (14.7±9.2%) (p=0.003).t90was abnormal in the wheeze (8.0±5.0%) and chILD (32.7±25.8%) groups and higher in the chILD group than in the controls (p&lt;0.001). HRT1 negatively correlated witht90in all groups.ConclusionSignificant differences in HVR timing and magnitude were noted in the chILD, wheeze and control groups. A relationship between nocturnal hypoxaemia and HRT1 was proposed. HVR characterisation may help identify patients with abnormal nocturnalSpO2.

Nocturnal oxygen saturation is associated with all-cause mortality: a community-based study.

Observational studies have demonstrated the association between the single-point measurement of oxygen saturation (SpO2) level and mortality in the general population. This study aimed to evaluate whether nocturnal SpO2 level could predict all-cause mortality in a community-based population. The study samples were obtained from the Sleep Heart Health Study, which included 2,280 men and 2,606 women (mean age, 63.8 ± 11.1 years). A pulse oximeter based on overnight in-home polysomnography was used to monitor SpO2 levels during total sleep time (SpO2-TOTAL). Multivariable Cox proportional hazards analysis was performed to examine the association between nocturnal SpO2 and all-cause mortality. During the follow-up period of 10.7 ± 3.0 years, 1,110 (22.7%) people died. After adjusting for confounding factors, multivariable Cox regression analysis showed that the average SpO2-TOTAL (hazard ratio [HR] 0.93; 95% confidence interval [CI] 0.90-0.96, P < .001) was associated with all-cause mortality. These findings remained stable in individuals with low and high apnea-hypopnea index levels. Additionally, maximum SpO2-TOTAL (HR, 0.91; 95% CI, 0.87-0.96; P = .001) and minimum SpO2-TOTAL (HR, 0.98; 95% CI, 0.97-0.99; P = .001) could predict all-cause mortality. A significant association between nocturnal hypoxemia and all-cause mortality was also observed. Our findings highlight the importance of monitoring nocturnal SpO2 level and improving hypoxemia in the general populations. Yan B, Gao Y, Zhang Z, Shi T, Chen Q. Nocturnal oxygen saturation is associated with all-cause mortality: a community-based study. J Clin Sleep Med. 2024;20(2):229-235.

Sleep parameters in patients with chronic hypersensitivity pneumonitis: a case-control study.

To compare patients with chronic hypersensitivity pneumonitis (cHP) and controls with normal spirometry in terms of their sleep characteristics, as well as to establish the prevalence of obstructive sleep apnea (OSA) and nocturnal hypoxemia. Secondary objectives were to identify factors associated with OSA and nocturnal hypoxemia; to correlate nocturnal hypoxemia with the apnea-hypopnea index (AHI) and lung function, as well as with resting SpO2, awake SpO2, and SpO2 during exercise; and to evaluate the discriminatory power of sleep questionnaires to predict OSA. A total of 40 patients with cHP (cases) were matched for sex, age, and BMI with 80 controls, the ratio of controls to cases therefore being = 2:1. The STOP-Bang questionnaire, the Epworth Sleepiness Scale (ESS), the Pittsburgh Sleep Quality Index, the Berlin questionnaire and the Neck circumference, obesity, Snoring, Age, and Sex (NoSAS) score were applied to all cases, and both groups underwent full-night polysomnography. The patients with cHP had longer sleep latency, lower sleep efficiency, a lower AHI, a lower respiratory disturbance index, fewer central apneas, fewer mixed apneas, and fewer hypopneas than did the controls. The patients with cHP had significantly lower nocturnal SpO2 values, the percentage of total sleep time spent below an SpO2 of 90% being higher than in controls (median = 4.2; IQR, 0.4-32.1 vs. median = 1.0; IQR, 0.1-5.8; p = 0.01). There were no significant differences between cases with and without OSA regarding the STOP-Bang questionnaire, NoSAS, and ESS scores. The prevalence of OSA in cHP patients (cases) was high, although not higher than that in controls with normal spirometry. In addition, cases had more hypoxemia during sleep than did controls. Our results suggest that sleep questionnaires do not have sufficient discriminatory power to identify OSA in cHP patients.

Pulse oximetry values from 33,080 participants in the Apple Heart & Movement Study

Wearable devices that include pulse oximetry (SpO2) sensing afford the opportunity to capture oxygen saturation measurements from large cohorts under naturalistic conditions. We report here a cross-sectional analysis of 72 million SpO2 values collected from 33,080 individual participants in the Apple Heart and Movement Study, stratified by age, sex, body mass index (BMI), home altitude, and other demographic variables. Measurements aggregated by hour of day into 24-h SpO2 profiles exhibit similar circadian patterns for all demographic groups, being approximately sinusoidal with nadir near midnight local time, zenith near noon local time, and mean 0.8% lower saturation during overnight hours. Using SpO2 measurements averaged for each subject into mean nocturnal and daytime SpO2 values, we employ multivariate ordinary least squares regression to quantify population-level trends according to demographic factors. For the full cohort, regression coefficients obtained from models fit to daytime SpO2 are in close quantitative agreement with the corresponding values from published reference models for awake arterial oxygen saturation measured under controlled laboratory conditions. Regression models stratified by sex reveal significantly different age- and BMI-dependent SpO2 trends for females compared with males, although constant terms and regression coefficients for altitude do not differ between sexes. Incorporating categorical variables encoding self-reported race/ethnicity into the full-cohort regression models identifies small but statistically significant differences in daytime SpO2 (largest coefficient corresponding to 0.13% lower SpO2, for Hispanic study participants compared to White participants), but no significant differences between groups for nocturnal SpO2. Additional stratified analysis comparing regression models fit independently to subjects in each race/ethnicity group is suggestive of small differences in age- and sex-dependent trends, but indicates no significant difference in constant terms between any race/ethnicity groups for either daytime or nocturnal SpO2. The large diverse study population and study design employing automated background SpO2 measurements spanning the full 24-h circadian cycle enables the establishment of healthy population reference trends outside of clinical settings.

The Impact of Lung Function Parameters on Sleep Among Aboriginal Australians - A Polysomnography and Spirometry Relationship Study.

Sleep disorders such as obstructive sleep apnoea (OSA) are known to overlap significantly with airway diseases in various populations. This study assessed the relationship between lung function parameters against polysomnography (PSG) and continuous positive airway pressure (CPAP) adherence data amongst an Aboriginal Australian population. Patients who undertook both a diagnostic PSG and spirometry were included. Restrictive, obstructive, and mixed impairments were assessed via global lung function initiative (GLI-2012, ATS/ERS) criteria/guidelines. PSG and CPAP data were evaluated between patients with or without spirometry impairments. Of the total 771 patients, 248 had PSG and spirometry data available (52% female, 44% remote residents, 78% obese). The majority (89%) had OSA (51% severe), 95 (38%) were observed to have a restrictive impairment, and 31 (13%) had an obstructive or mixed impairment on spirometry. Compared to patients with no spirometric impairment, those with restrictive or obstructive/mixed impairments demonstrated significantly lower sleep efficiency (median 84% vs 79% and 78%), higher apnoea-hypopnea index (AHI) during rapid eye movement (REM) sleep (median 32 vs 52 and 55 events/hour), reduced REM oxygen saturation (SpO2) (median 94.0% vs 92.0% and 92.5%) and reduced adherence to CPAP therapy (median 39% vs 22% and 17%). Differences in sleep efficiency, REM AHI, and NREM SpO2 held for patients with obstructive/mixed impairments in multivariate modelling. Aboriginal Australian patients with OSA have a higher concurrent lung function' impairment. Spirometric impairment appears to negatively influence sleep efficiency, nocturnal SpO2 and CPAP adherence. This may have substantial implications for OSA management among Aboriginal Australians.

Predicting hypercapnia and hypoxia by the ventilator's built-in software in children on long-term non-invasive ventilation: A pilot study.

Follow-up of children on long-term non-invasive ventilation (NIV) could be improved by telemonitoring, using the ventilator's built-in software (BIS) parameters as alternative for in-hospital sleep studies to reduce costs, enhance patient independence and contribute to early detection of infections. This pilot study investigated whether analysis of BIS parameters can predict abnormal nocturnal transcutaneous CO2 (TcCO2) and saturation (SpO2) measurements in children on long-term NIV. Children on long-term NIV in follow-up at the Antwerp University Hospital were retrospectively included. Nocturnal TcCO2 and SpO2 measurements were collected together with BIS parameters at three different time points: the night of the sleep study (BIS1), mean values from 48 h (BIS2) and 72 h (BIS3) before the sleep study. Predictions were calculated for following outcome measures: % recording time TcCO2 > 46.9 mmHg (%RT TcCO2; abnormal if ≥2%), recording time SpO2 < 93% (RT SpO2; abnormal if >1 h), abnormal TcCO2 or SpO2, mean TcCO2, mean SpO2. 69 patients were included. %RT TcCO2 was separately predicted by reached tidal volume2 [OR 0.97 (0.93; 1.00); p = 0.051; AUC = 30%] and reached IPAP1 [OR 1.05 (1.00; 1.10); p = 0.050; AUC = 66%]. Leak1 predicted RT SpO2 [OR 1.21 (1.02; 1.43); p = 0.025; AUC = 84%]. Mean TcCO2 correlated with reached tidal volume2 (R2 0.10, p = 0.033). Certain BIS parameters can predict nocturnal hypercapnia and desaturation in children on long-term NIV. Future studies with larger sample sizes are warranted to further investigate the predictive value of the identified BIS parameters.

Sleep and cardiometabolic comorbidities in the obstructive sleep apnoea-COPD overlap syndrome: data from the European Sleep Apnoea Database.

The impact of obstructive sleep apnoea (OSA)-COPD overlap syndrome (OVS) on sleep quality and cardiovascular outcomes has not been fully explored. We aimed to compare clinical and polysomnographic characteristics of patients with OVS versus patients with OSA, and to explore pathophysiological links between OVS and comorbidities. This cross-sectional analysis initially included data from 5600 patients with OSA and lung function in the European Sleep Apnoea Database. Two subgroups of patients with OSA (n=1018) or OVS (n=509) were matched (2:1) based on sex, age, body mass index and apnoea-hypopnea index at baseline. After matching, patients with OVS had more severe hypoxia, lower sleep efficiency and presented with higher prevalences of arterial hypertension, ischaemic heart disease and heart failure compared with patients with OSA. OVS was associated with a significant decrease in sleep efficiency (mean difference (β) -3.0%, 95% CI -4.7 to -1.3) and in nocturnal mean peripheral oxyhaemoglobin saturation (SpO2) (β -1.1%, 95% CI -1.5 to -0.7). Further analysis revealed that a decrease in forced expiratory volume in 1 s and arterial oxygen tension was related to a decrease in sleep efficiency and in mean nocturnal SpO2. A COPD diagnosis increased the odds of having heart failure by 1.75 (95% CI 1.15-2.67) and systemic hypertension by 1.36 (95% CI 1.07-1.73). Nocturnal hypoxia was strongly associated with comorbidities; the mean nocturnal SpO2 and T90 (increase in time below SpO2 of 90%) were associated with increased odds of systemic hypertension, diabetes and heart failure but the oxygen desaturation index was only related to hypertension and diabetes. Patients with OVS presented with more sleep-related hypoxia, a reduced sleep quality and a higher risk for heart failure and hypertension.

A New Device for Remote Monitoring of Vital Parameters in Acromegalic Patients: Pilot Study.

Acromegaly is a rare disease that results from growth hormone (GH) excess. Diabetes mellitus, hypertension,cardiomyopathy, and obstructive sleep apnoea syndrome( OSAS) are frequent complications. Identify a useful system to obtain a reliable remote monitoring of glucose and the most important vital parameters in the acromegalic subjects. Sixteen acromegalic patients (from 30 to 73 years old) were enrolled. We provided health monitor devices to the patients for continuous acquisition of physiological signals including twelve-lead electrocardiography (EKG) and nocturnal SpO2. At the same time, we applied on the same patients the blinded continuous glucose monitoring system(CGMS). The lowest saturation peaks at night (<80%) were achieved in patients with a known diagnosis of OSAS. A positive correlation was demonstrated between the lowest oxygen saturation values and the CGM peaks (pV <0,0001) and between the average values of oxygen saturation and CGM (pV<0,0003). Patients with a previous diagnosis of OSAS, obtained by polysomnography, showed on the multiparametric monitor recordings superimposable to their known condition. Instead we noticed a discordance in the two EKG recording: the wireless mode showed an irregular rhythm in 5/16 patients, which was not confirmed by the recording mode with cables. The health monitor device associated with CGM may be a new useful and versatile tool for fragile patients who can self-manage remote monitoring, and for physicians who can obtain real-time information for the clinical and therapeutic management of patients. It is also a useful tool for the follow-up of patients with OSAS. Moreover, once the interference of the OSAS is excluded, the CGM allows us to obtain a more reliable and accurate diagnosis of DM.

Sex-specific differences in sleep-disordered breathing and nocturnal hypoxemia in chronic thromboembolic pulmonary hypertension and chronic thromboembolic pulmonary disease.

Although chronic thromboembolic pulmonary hypertension (CTEPH) and chronic thromboembolic pulmonary disease (CTEPD) are known to be accompanied by symptoms associated with sleep-disordered breathing (SDB) and nocturnal hypoxemia, the sex-specific differences of SDB and nocturnal hypoxemia in patients with CTEPH and CTEPD remain unknown. Between July 2020 and August 2022, data were retrieved from 57 males and 63 female patients with CTEPH and CTEPD who underwent sleep study at Shanghai Pulmonary Hospital. Nocturnal mean SpO2 (mean SpO2) < 90% was defined as nocturnal hypoxemia. Logistic and linear regression analysis was performed to assess the predictive value of sleep study indices to hemodynamic parameters. Receiver operating characteristic (ROC) curve was applied to analyze the specific parameters to predict the risk of CTEPH. SDB was similarly present in males and females, and both sexes predominantly had obstructive sleep apnea (OSA); more women were diagnosed with nocturnal hypoxemia (32 vs. 7%, p = 0.002). SaO2 was negatively associated with mean pulmonary arterial pressure (mPAP) in men (p < 0.001), whereas the ratio of nocturnal SpO2 < 90% of the total monitoring time (T90%) was positively correlated with mPAP. Mean SpO2 was an independent predictor for pulmonary vascular resistance and cardiac output in women (p = 0.001, p < 0.001, p = 0.001, respectively). T90%, SaO2, and minimal SpO2 were combined to develop a new composite parameter: hypoxemia scoring index (HSI). ROC curve analysis indicated that HSI levels of 0.55 could discriminate CTEPH from CTEPD with a sensitivity of 92.3% and specificity of 87.5% in female patients (an area under the curve, 0.937; 95% CI: 0.879-0.995, p < 0.001). Sex-specific nocturnal hypoxemia was present in patients with CTEPH or CTEPD. In female patients, the HSI showed high capacity for predicting the risk of CTEPH. Registry: chictr.org.cn; Identifier: ChiCTR-DDD-16009406.

Nocturnal hypoxemia, blood pressure, vascular status and chronic mountain sickness in the highest city in the world

Introduction Chronic mountain sickness (CMS) is a condition characterized by excessive erythrocytosis in response to chronic hypobaric hypoxia. CMS frequently triggers cardiorespiratory diseases such as pulmonary hypertension and right or left heart failure. Ambient hypoxia might be further amplified night-time by intermittent hypoxia related to sleep-disordered breathing (SDB) so that sleep disturbance may be an important feature of CMS. Our aim was to characterize in a cross-sectional study nocturnal hypoxaemia, SDB, blood pressure (BP), arterial stiffness and carotid intima-media thickness (CIMT) in highlanders living at extreme altitude. Methods Men aged 18 to 55 years were prospectively recruited. Home sleep apnoea test, questionnaires (short-form health survey; Montreal cognitive assessment; Pittsburgh Sleep Questionnaire Index and the Insomnia severity index), 24-h ambulatory BP monitoring, CIMT and arterial stiffness were evaluated in 3 groups: i) Andean lowlanders (sea-level); ii) highlanders living at 3,800 m and iii) highlanders living at 5,100 m. Analyses were conducted in sub-groups according to 1) CMS severity 2) healthy subjects living at the three different altitude. Results Ninety-two males were evaluated at their living altitudes. Among the 54 highlanders living at 5,100 m, subjects with CMS showed lower mean nocturnal oxygen saturation (SpO2), SpO2 nadir, lower pulse wave velocity and higher nocturnal BP variability than those with no-CMS. Lower nocturnal SpO2 nadir was associated with higher CMS severity (ß= −0.14, p=.009). Among the 55 healthy subjects, healthy highlanders at 5,100 m were characterized by lower scores on quality of life and sleep quality scales and lower mean SpO2 compared to lowlanders. Conclusions Lower nocturnal SpO2 and higher nocturnal BP variability are associated with CMS severity in individuals living permanently at high altitude. The role of lower SpO2 and higher nocturnal BP variability in the cardiovascular progression of CMS and in the overall prognosis of the disease need to be evaluated in further studies.

The association between sleep disturbances and neurocognitive function in pediatric sickle cell disease

Background and objectiveYouth with sickle cell disease (SCD) without neurological complications continue to be at increased risk of neurocognitive difficulties. Nocturnal hypoxemia is associated with neurocognitive outcomes and has been identified as a chronic complication in youth with SCD. The objective of this study was to assess the relationship between sleep disturbances and neurocognitive functioning in youth with SCD, while taking into account demographic and socioeconomic factors. MethodsYouth with SCD were identified through retrospective chart review who underwent a standardized polysomnography (PSG) and completed a neuropsychological testing battery to assess cognitive skills, including verbal comprehension, working memory, processing speed, and cognitive flexibility. Questionnaires were also collected to assess parent-reported concerns with their youth's executive and adaptive skills. ResultsTwenty-seven youth with SCD, ages 6–17, were identified who completed both a PSG and neuropsychological testing. Results demonstrated that verbal comprehension decreased by 2.37 standard points for every unit decrease in mean nocturnal oxygen saturation (SpO2) (p = 0.031). Working memory was also found to decrease by 1.46 standard points for each 1% increase in time spent under 90% oxygen saturation (pTST SpO2 < 90%) (p = 0.030). Sleep parameters did not significantly predict other cognitive scores or parent-reported executive or behavioral ratings. ConclusionOur study found that sleep disturbance, mean nocturnal SpO2 and pTST SpO2 < 90%, significantly affected verbal comprehension and working memory performance, respectively. Overall, these findings have the potential to identify sleep needs in youth with SCD to promote sleep-targeted interventions as a modifiable factor to reduce neurocognitive deficits.

Assessment of the effect of the dual orexin receptor antagonist daridorexant on various indices of disease severity in patients with mild to moderate obstructive sleep apnea

BackgroundThe dual orexin receptor antagonist daridorexant did not impact nighttime respiratory function as assessed by the apnea/hypopnea index (AHI) and nocturnal oxygen saturation (SpO2) and improved sleep in patients with mild to moderate obstructive sleep apnea (OSA). These analyses were supplemented with further evaluations of various indices of OSA severity and sleep variables. MethodsIn this randomized, double-blind, placebo-controlled, two-period, crossover study, 50 mg daridorexant or placebo was administered every evening for 5 days to 28 patients with mild to moderate OSA. Treatment differences (daridorexant – placebo) were explored for indices of OSA severity including the number and duration of apneas and hypopneas, mean and lowest nocturnal SpO2, sleep duration during each hour of polysomnography recording, and the number and mean and longest duration of awakenings. ResultsAfter repeated-dose daridorexant, more respiratory events were observed compared to placebo, ie., treatment difference of 16.4 events (90% confidence interval: −0.4, 33.2) which is explained by a longer total sleep time. However, no treatment difference was detected for the longest duration of apneas and hypopneas (1.5 s [–8.3, 11.2] and 8.2 s [–6.6, 23.0], respectively), and lowest SpO2 (0.9% [–0.3, 2.1]). The number of awakenings was similar between daridorexant and placebo while daridorexant shortened the longest duration by 16.2 min (8.5, 23.8).Overall, results were similar after single and repeated dosing for both respiratory and sleep aspects. ConclusionThese results suggest safe use of daridorexant in patients with mild to moderate OSA. Clinical trial registrationClinicalTrials.gov NCT03765294. A study to investigate the effects of ACT-541468 on nighttime respiratory function in patients with mild to moderate obstructive sleep apnea. https://clinicaltrials.gov/ct2/show/NCT03765294.

Prospective Study of Nocturnal Desaturation in Patients Receiving Home Oxygen Therapy.

Objective Nocturnal desaturation is common in patients with chronic respiratory disease and often worsens the prognosis. Therefore, it should be diagnosed accurately and appropriately treated. The aim of this study was to clarify the diversity of nocturnal desaturation. Methods We prospectively enrolled 58 outpatients diagnosed with chronic respiratory disease receiving home oxygen therapy and measured nocturnal SpO2 using a portable oximeter. We classified nocturnal desaturation (3% decrease in SpO2 from baseline) into three patterns: periodic pattern (desaturation duration of <655 seconds), sustained pattern (desaturation duration of ≥655 seconds), and intermittent pattern (desaturation and recovery of SpO2 repeated with a cycle of several minutes). Results Nocturnal hypoxemia (SpO2 ≤88% for more than 5 minutes) was found in 23.8% of patients. The percentage of patients with chronic obstructive pulmonary disease (COPD) was significantly higher in the nocturnal hypoxemia group than in the non-hypoxemia group (80% vs. 40.6%, p=0.03). Desaturation with a periodic pattern was found in 81% of patients, desaturation with a sustained pattern was found in 40.5% of patients, and desaturation with an intermittent pattern was found in 59.5% of patients. In patients with COPD, desaturation with a periodic pattern was found in 85.7%, desaturation with a sustained pattern was found in 47.6%, and desaturation with an intermittent pattern was found in 57.1%. Conclusion The SpO2 waveform of nocturnal hypoxemia was able to be classified into three patterns. Suitable treatment for each pattern might improve the prognosis of these patients.

Analysis of nocturnal desaturation waveforms using algorithms in patients with idiopathic pulmonary fibrosis

PurposeSleep-disordered breathing is recognized as a comorbidity in patients with idiopathic pulmonary fibrosis (IPF). Among them, nocturnal hypoxemia has been reported to be associated with poor prognosis and disease progression. We developed a diagnostic algorithm to classify nocturnal desaturation from percutaneous oxygen saturation (SpO2) waveform patterns: sustained pattern, periodic pattern, and intermittent pattern. We then investigated the prevalence of nocturnal desaturation and the association between the waveform patterns of nocturnal desaturation and clinical findings of patients with IPF.MethodsWe prospectively enrolled patients with IPF from seven general hospitals between April 2017 and March 2020 and measured nocturnal SpO2 and nasal airflow by using a home sleep apnea test. An algorithm was used to classify the types of nocturnal desaturation. We evaluated the association between sleep or clinical parameters and each waveform pattern of nocturnal desaturation.ResultsAmong 60 patients (47 men) who met the eligibility criteria, there were 3 cases with the sustained pattern, 49 cases with the periodic pattern, and 41 cases with the intermittent pattern. Lowest SpO2 during sleep and total sleep time spent with SpO2 < 90% were associated with the sustained pattern, and apnea–hypopnea index was associated with the intermittent pattern.ConclusionWe demonstrated the prevalence of each waveform and association between each waveform and sleep parameters in patients with IPF. This classification algorithm may be useful to predict the degree of hypoxemia or the complication of obstructive sleep apnea.

Sleep-Disordered Breathing and Nocturnal Hypoxemia in Precapillary Pulmonary Hypertension: Prevalence, Pathophysiological Determinants, and Clinical Consequences

Background and objective: The clinical relevance and interrelation of sleep-disordered breathing and nocturnal hypoxemia in patients with precapillary pulmonary hypertension (PH) is not fully understood. Methods: Seventy-one patients with PH (age 63 ± 15 years, 41% male) and 35 matched controls were enrolled. Patients with PH underwent clinical examination with assessment of sleep quality, daytime sleepiness, 6-minute walk distance (6MWD), overnight cardiorespiratory polygraphy, lung function, hypercapnic ventilatory response (HCVR; by rebreathing technique), amino-terminal pro-brain natriuretic peptide (NT-proBNP) levels, and cardiac MRI (n = 34). Results: Prevalence of obstructive sleep apnea (OSA) was 68% in patients with PH (34% mild, apnea-hypopnea index [AHI] ≥5 to <15/h; 34% moderate to severe, AHI ≥15/h) versus 5% in controls (p < 0.01). Only 1 patient with PH showed predominant central sleep apnea (CSA). Nocturnal hypoxemia (mean oxygen saturation [SpO₂] <90%) was present in 48% of patients with PH, independent of the presence of OSA. There were no significant differences in mean nocturnal SpO₂, self-reported sleep quality, 6MWD, HCVR, and lung and cardiac function between patients with moderate to severe OSA and those with mild or no OSA (all p > 0.05). Right ventricular (RV) end-diastolic (r = −0.39; p = 0.03) and end-systolic (r = −0.36; p = 0.04) volumes were inversely correlated with mean nocturnal SpO₂ but not with measures of OSA severity or daytime clinical variables. Conclusion: OSA, but not CSA, is highly prevalent in patients with PH, and OSA severity is not associated with nighttime SpO₂, clinical and functional status. Nocturnal hypoxemia is a frequent finding and (in contrast to OSA) relates to structural RV remodeling in PH.

Nocturnal cerebral tissue oxygenation in lowlanders with chronic obstructive pulmonary disease travelling to an altitude of 2,590m: Data from a randomised trial.

Altitude exposure induces hypoxaemia in patients with chronic obstructive pulmonary disease (COPD), particularly during sleep. The present study tested the hypothesis in patients with COPD staying overnight at high altitude that nocturnal arterial hypoxaemia is associated with impaired cerebral tissue oxygenation (CTO). A total of 35 patients with moderate-to-severe COPD, living at <800m (mean [SD] age 62.4[12.3]years, forced expiratory volume in 1s [FEV1 ] 61[16]% predicted, awake pulse oximetry ≥92%) underwent continuous overnight monitoring of pulse oximetry (oxygen saturation [SpO2 ]) and near-infrared spectroscopy of prefrontal CTO, respectively, at 490m and 2,590m. Regression analysis was used to evaluate whether nocturnal arterial desaturation (COPDDesat , SpO2 <90% for >30% of night-time) at 490m predicted CTO at 2,590m when controlling for baseline variables. At 2,590m, mean nocturnal SpO2 and CTO were decreased versus 490m, mean change -8.8% (95% confidence interval [CI] -10.0 to -7.6) and -3.6% (95% CI -5.7 to -1.6), difference in change ΔCTO-ΔSpO2 5.2% (95% CI 3.0 to 7.3; p<.001). Moreover, frequent cyclic desaturations (≥4% dips/hr) occurred in SpO2 and CTO, mean change from 490m 35.3/hr (95% CI 24.9 to 45.7) and 3.4/hr (95% CI 1.4 to 5.3), difference in change ΔCTO-ΔSpO2 -32.8/hr (95% CI -43.8 to -21.8; p<.001). Regression analysis confirmed an association of COPDDesat with lower CTO at 2,590m (coefficient -7.6%, 95% CI -13.2 to -2.0; p=.007) when controlling for several confounders. We conclude that lowlanders with COPD staying overnight at 2,590m experience altitude-induced hypoxaemia and periodic breathing in association with sustained and intermittent cerebral deoxygenation. Although less pronounced than the arterial deoxygenation, the altitude-induced cerebral tissue deoxygenation may represent a risk of brain dysfunction, especially in patients with COPD with nocturnal hypoxaemia at low altitude.

Galectin-3 and neutrophil-to-lymphocyte ratio are indicative of heart remodelling and disease severity in patients with obstructive sleep apnoea

BackgroundGalectin-3, considered as a new inflammatory marker; it is increased in cardiovascular disease. We investigated Galectin-3 in relation to heart damage in patients with OSA and its role in inflammation, based on the Neutrophil-to-Lymphocyte Ratio (NLR). MethodsSixty-three consecutive patients (45 males, 18 females, 58.60 ± 12.28 years old) were studied. According to the Apnoea–Hypopnoea Index (AHI) patients were divided into Group 1 – non-severe (AHI <30) (17 males and 10 females, 59.89 ± 10.62 years old) and Group 2 – severe (AHI ≥30) (29 males and 6 females, aged 57.53 ± 13.30 years old) OSA. All patients underwent morning blood gas analysis, laboratory tests, nocturnal polygraphy, and echocardiography. ResultsGalectin-3 was significantly increased in Group 2 (p = 0.027) patients. Moreover, it was directly related to left ventricle (LV) mass, left ventricle hypertrophy and LV posterior wall diameter. Tissue Doppler septal velocity (e′), that measures wall motion, was inversely correlated to Galectin-3. Furthermore, a direct association to diastolic dysfunction, evaluated as E/e′ ratio, was observed. In line with these data, a direct correlation between Galectin-3 and left atrium volume was also found. Galectin-3 and percentage of total registration time with nocturnal oxygen saturation <90% (TST90) were directly correlated (p = 0.0003), while Galectin-3 and mean nocturnal SpO2 were negatively correlated (p = 0.0045). We found a direct correlation between Galectin-3 and NLR (p = 0.011). Finally, Galectin-3 was able to predict 3-yr mortality with a specificity of 83.33% and a sensitivity of 91.84%. ConclusionGalectin-3 showed a direct association to nocturnal respiratory indices and to cardiac remodelling in patients with OSA. OSA-induced inflammation may play an important role in the pathogenesis of heart damage.